As mentioned here, updates to Camera Raw 8 for Photoshop CS6 only include new camera support, lens profile support, and bug fixes. The new features listed here are only available in Photoshop CC.
Here’s an overview of my favorite features:
1) Previews – Camera Raw can now display a before/after Preview (with aside-by-side and split-view support) to compare your edits to the original. The Preview check box in earlier versions of ACR has been replaced by three buttons in the bottom-right of the ACR main dialog. From left to right, they are Mode, Swap and Copy:
Click the Mode button to cycle through left/right and top/bottom side-by-side and split-view modes.
• Click-and-hold the Mode button to bring up a popup menu for directly choosing Preview modes and accessing the Preview Preferences (the Preview Preferences support customizing the Preview modes used for cycling as well as some drawing options including divider and pane options).
•Tap Q to cycle through the Preview modes.
Click the Swap button to swap Before/After settings.
• Tap P to swap Before/After settings for the primary selected image only.
• Shift + P to swap Before/After settings for all selected images.
Click the Copy button to copy the After settings to the Before settings. This is useful for establishing a temporary “checkpoint” for your image editing session.
• Option + P (Mac) | Alt + P (Win) to copy After settings to the Before settings for the primary selected image only.
• Option + Shift + P (Mac) | Alt + Shift + P (Win) to copy After settings to the Before settings for all selected images.
Additional Notes: with regards to Previews: when making changes to images, the changes can only be made to the “after” image and the slider settings (in the panels) will always reflect the “after” image settings. The standard single-image view always shows the “after state”. Zooming and panning on one view will automatically zoom and pan the other.
2) Local correction changes – you can now easily reset all sliders when using the selective adjustment tools (Graduated and Radial filter and Adjustment Brush) by Control -clicking (Mac) | Right Mouse -clicking (Win) on the pin and choosing “Reset Local Correction Settings” from the context menu. Or, you can use the flyout menu to choose “Reset Local Correction Settings” – whichever is faster for you.
Previously, double clicking inside of a Radial Filter set it to fill the image bounds. This still works, however Control -click (Mac) | Right Mouse -click (Win) on the pin and choosing Fill Image accomplishes the same thing.
3) When synchronizing, creating new presets, saving settings (all in ACR) and copy and pasting settings (in Bridge), you can now single-click a button to check all/none.
4) Tap X when using the Crop Tool or Straighten Tool to flip the crop aspect ratio (landscape to portrait, portrait to landscape).
5) The Grain effect now varies from image to image to facilitate editing time-lapse and video frame sequences.
6) Control -click (Mac) | Right Mouse -click (Win) within the Histogram to enable Lab color readouts, even when the Workflow Options are set to another color space (such as Adobe RGB). Note: the context menu can also be used to toggle the shadow, highlight, and gamut clipping warnings.
7) There are several new color matching profiles for Fuji X-Trans customers that emulate the camera presets including Provia (Standard), Velvia (Vivid), Astia (Soft) etc.. For a full list of supported cameras, click here.
8) The Red Eye tool can now correct bright pupils in animals. Select the tool and, in the Red Eye Removal panel, Select ‘Pet Eye’ from the drop down menu to locate and fix pet eyes. You can also automatically add catchlights and drag to reposition them.
In addition, ACR 8.4 RC adds new camera support and bug fixes. Click here for more detailed information.
Note: Camera Raw 8.4 and DNG Converter 8.4 are no longer officially supported on the following platforms: Mac OS 10.6.x (Snow Leopard), Windows XP, and Windows Vista.